1. Field of the Invention
This invention relates to a method and apparatus for driving an elongate member through the ground. More particularly, this invention relates to a method and apparatus for driving rod and pipe under embankments, roadways and the like using a driving mechanism which forces the pipe or rods through.
2. Description of the Prior Art
In the installation of pipelines, it is frequently necessary to install pipelines under roadways, driveways, embankments, or similar obstructions. Traditionally, a pipeline is installed under such obstructions by excavating a trench, lowering the pipeline in place and refilling the trench. However, this is not the preferred technique because it interferes with traffic in the case of a roadway, for example. Furthermore, digging trenches is expensive and time consuming. An alternative approach has been the use of conventional water or air drilling methods which use a rotary bit. Using these methods, a tunnel is excavated under the roadway or embankment prior to the installation of the pipeline. Again, this can be expensive, particularly in the case of larger pipelines because of the diameter of the tunnel required to accommodate the pipeline. Furthermore, the removal of the soil and other debris from both sides of the roadway or embankment as the tunnel is dug causes logistical problems, particularly if the trench dug to accommodate the drilling apparatus fills up.
A more satisfactory approach has been the use of compressive pipe pushing apparatus which force the pipe under the roadway or embankment. This is especially advantageous because it does not require a trench across the roadway which interferes with the traffic or the need to pre-drill a passageway or tunnel. However, even using pipe pushing apparatus there are disadvantages. For example, the prior art apparatus require a long trench to accommodate the frame assembly because the driving mechanism, which is usually hydraulic cylinders, is positioned behind the pipe segment to be driven. For example, U.S. Pat. No. 3,711,067 discloses a pipe pushing apparatus which uses a hydraulic cylinder 30 positioned behind the pipe segment 44 for moving pipe in a stepwise fashion. This motion is provided by a segment plate 9 advanced between frame members 1/2. U.S. Pat. Nos. 3,726,506 and 3,834,668 disclose other forms of pipe pushing apparatus. Again, in both of these references, the hydraulic cylinders are located behind the pipe segment being driven and the apparatus includes a fairly complicated gripping structure to engage the pipe prior to displacement. See also U.S. Pat. Nos. 4,020,641; 4,251,058; 4,299,375; 4,434,969; and 4,502,665.
U.S. Pat. Nos. 4,159,819; 4,082,248; and 3,358,966 disclose other types of apparatus used to drive larger diameter pipe primarily for roof support in larger tunnels such as railway or subway tunnels. U.S. Pat. No. 4,159,819 describes a pipe pushing apparatus having dual hydraulic cylinders 16 which push against tension members 18. Using clamping devices 22, the pistons advance the tension members forward which advance a collar 15 that pushes against the end of pipe 11. When the hydraulic cylinders are fully extended, the clamping devices are relocated on the tension members permitting another full extension of the hydraulic cylinders. U.S. Pat. No. 4,082,248 discloses an internally mounted pipe pushing apparatus which stations itself within the pipe to be driven. Hydraulic rams 11 engage on abutment means 17 advancing the pipe 12 forward. Once fully extended, a second section of pipe 12A is added, and the apparatus is retracted into the new section and reengaged. The process is repeated. U.S. Pat. No. 3,358,966 discloses an apparatus having pairs of rails 14 and 15 located circumferentially around a pipe 13. Hydraulic cylinders 17 push against these rails and against the ends of the pipe to advance the pipe through the ground. The pipe is advanced in a stepwise manner along the rails using keys 18 inserted in holes 19. See also U.S. Pat. No. 4,576,514.
However, the need exists for an improved pipe pushing apparatus and method for installing small diameter pipe. More particularly, the need exists for an apparatus which is only slightly longer in length than a segment of pipe but includes the capability of installing one or multiple pipe segments simultaneously using hydraulic cylinders small enough in size not to appreciably affect the overall size of the apparatus.